28.3.2.6 Multipacket Transfer

A Multipacket transfer enables a data payload exceeding the endpoint maximum data payload size to be transferred as multiple packets without software intervention, reducing interrupts and software intervention to higher level USB transfer, not each packet. The Multipacket transfer is identical to the IN and OUT transactions described above unless noted in this section. The Multipacket does not require any special consideration on the host side. The Multipacket transfer is not recommended for isochronous endpoints except when used to write-protect buffers smaller than the endpoint size.

The Multipacket is enabled by writing a ‘1’ to the Multipacket Transfer Enable (MULTIPKT) bit in the Endpoint Control (EP[n].[dir].CTRL) register.

The Multipacket Byte Count (EP[n].[dir].MCNT) and Endpoint Data Pointer (EP[n].[dir].DATAPTR ) registers are used to setting the size and address of the RAM buffer to be processed by the USB peripheral for a specific endpoint. The USB peripheral will split the required USB data transfers buffer without software intervention.